This invention relates to heating, ventilating and air conditioning systems, and more particularly to a novel and improved air mixing apparatus for optimized mixing of air passing through a space or duct while maintaining a uniform velocity profile and minimum pressure drop.
Airstreams which are introduced at different temperature levels through a common duct in ventilating and air conditioning systems require intimate mixing in the duct in order to avoid undesirable stratification of the air prior to, for example, its passage into a room air space. The static mixing device disclosed in U.S. Pat. No. 4,495,858 and assigned to the assignee of this invention, when interposed in such a duct, effectively minimizes stratification of the different temperature airstreams in the duct.
An air mixing or blending apparatus installed in an air duct creates a pressure drop in the air flow across the blender during operation. This pressure drop is undesirable and therefore efforts to minimize the pressure drop is a main consideration in static air mixing design. In addition it is desirable to maximize the efficiency and effectiveness of the mixing that takes place immediately downstream of the mixing apparatus to achieve and to maintain a uniform velocity profile downstream of the mixing device. Conventional mixers have a mixing effectiveness typically less than 30% and at the most, about 38%. Therefore there is a need for development of a mixing apparatus which optimally mixes stratified airstreams of different temperatures while at the same time minimizing the pressure drop across the device and presents a relatively uniform velocity and temperature profile downstream of the apparatus.